Electrical reliability characteristics and dielectrics degradation in gate stacks (REO-HfO2) grown on the high mobility Ge substrates

Gate stacks (rare-earth oxides, REOs-HfO₂) grown on Germanium substrates using REOs (e.g. CeO₂, Dy₂O₃, La₂O₃) as an interfacial buffer layer which are also friendly with Ge, demonstrating better passivation and electrical properties [1]. However, it is imperative to study a number of reliability concerns such as, accumulation of charge at the interface of the two dielectric, charge trapping, defects generation, SILC and oxides degradation issues to understand completely the gate stacks. The films were prepared by MBE on p-type (001) Ge substrates with resistivity of 1.6-1.9 Ω-cm. The oxides were deposited at temperature 225°C. Pt was used as the gate electrode while the back ohmic contact was realized using eutectic In-Ga alloy. The present work we report electrical reliability and dielectrics degradation of Dy₂O₃/HfO₂ gate stacks during constant voltage stress (CVS) and all the measurements were performed at accumulation and room temperature condition.